1. Field of the Invention
The present invention relates to data communication systems and, more specifically, to a data communication system employing a unidirectional data ring.
2. Description of the Prior Art
Certain types digital communication chips require high speed distribution of streaming data between several different communicating entities. Certain applications require several different data streams to operate in parallel at a high bandwidth. For example, a processor may stream data to a memory for buffering and then the memory may stream the buffered data to an input/output circuit (I/O). At the same time new data may be streaming through the I/O to a memory buffer, and then to the processor. This type of application has a forward flow (from processor to I/O) and a backward flow (from I/O to processor) operating at the same time.
This high speed and parallel interconnection can be accomplished using several approaches, including: a full crossbar switch, a partially populated crossbar switch, a multi-ring bus, and a standard multi-drop bus. A ring bus is a good approach for very high bandwidth applications that require very large buses. The ring bus can interconnect various units in a ring using a large data bus.
As shown in FIG. 1, a bi-directional ring may be employed to allow back communication of data. In the example shown, a plurality of communicating entities 18 are coupled to both a first data ring 10 that transmits data in a first direction and a second data ring 12 that transmits data in a second direction, opposite from the first direction. Each communicating entity 18 is coupled to the first data ring 10 and the second data ring 12 with an access unit 14, which is a device that multiplexes an incoming data packet to its intended destination.
As performance requirements increase, wider busses must be employed. The increased width of a data ring bus results in more chip area being dedicated to the data ring and more complex wiring. Employing a bi-directional ring results in twice the wiring and chip area being dedicated to data communication.
Therefore, there is a need for a single data communication ring that facilitates simultaneous data transmission in both directions between more than a single entity.